Nigeria was granted independent in 1960 by Britain, ever since she has been playing a fatherly role in the African continent, some of the roles include laying a solid foundation for the establishment of ECOWAS with her continent sister Togo, she also played a lead role in peace keeping missions in Africa . Also to mention is the supply of electricity to neighbouring countries, to mention but a few with these one can conclude by saying Nigeria is truly a blessing to Africa.
I'm not from Nigeria, but I hear horror stories about the country and they are not doing good as well since their independent. So not sure though if you can call it a blessing to Africa as almost all the continents are also suffering.
And most of them rely to countries like China, UK and the US or even Saudi, so it's not that they are all independent. And it might take centuries as well to recover from all the destruction and other ill effects of being under colonialism for hundreds of years. And then there is the corruption that plague not just Nigeria but it's neighboring countries as well so it's not they are a role model or taking the lead.